T7 Earth Surface Processes in Tectonically Active and Unstable Regions I

Sunday, 22 September 2024
8:00 AM - 12:00 PM
210B

THE SOURCE OF 2023.10. 7-15 (MW 6.3) NORTH HERAT EARTHQUAKES: AŞKABAT-HERAT-MEZAR-I ŞERIF FOLD AND THRUST BELT

Paper number: T7-5
Program: Technical Sessions
Time: 9:00 AM – 9:15 AM

Authors

Abstract

The 2023 Herat earthquake sequence, a series of five earthquakes with moment magnitudes (Mw) ranging from 5.9 to 6.3, struck northwestern Afghanistan near Herat City (October 7-15, 2023). This event resulted in significant casualties (at least 2400 fatalities and over 2000 injuries) and highlights the need for a better understanding of regional tectonics.

The epicenter distribution of the earthquakes is located on the north of Herat and their focal mechanism solutions indicate east-west trending nearly pure thrust faults. This is a surprising result, because only known active structure in this region is the right-lateral strike-slip Herat Fault Zone. However, the epicenter distribution is far away to interpret these seismic events within a restraining stepover along the Herat Fault Zone. The preliminary InSAR data demonstrate a regional uplift around the epicenter locations in the north of Herat city.

High-resolution satellite imagery (Google Earth Pro) and digital elevation models (DEM-5m) were employed for detailed analysis of potential active thrust structures in the region that is on the north of a meeting point of the NE-SW trending right-lateral Herat Fault Zone and the NW-SE trending left-lateral Doruneh Fault Zone. We recognize presence of previously unidentified "blind thrust/back-thrust" faults by using fault propagation folds (mainly asymmetrical anticlines). These faults, trending northwest-southeast in the west (around Aşkabat) and east-west/east-northeast to west-southwest in the Herat and Mezar-ı Şerif regions, are characteristic of the Aşkabat-Herat-Mezar-ı Şerif (AHM) Fold and Thrust Belt. The re-interpretation of previous earthquakes under the light of AHM Fold and Thrust Belt including tear faults would contribute to broader advancements in our understanding of earthquake processes associated with double-vergent fold and thrust belts along the collision of Arabian/Indian and Eurasian plates.

Geological Society of America Abstracts with Programs. Vol. 56, No. 5

doi: 10.1130/abs/2024AM-401000

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